Search form

Audubon Report Finds Sprawl Cause of Sharp Decline in Birds

The loss of habitat which has caused bird numbers to plummet across America in recent decades has had an impact on the Vineyard, but not nearly as heavily as in other places, according to local experts.

They were commenting on a recent report by the National Audubon Society, which found suburban sprawl, land clearing for agriculture and global warming has caused a number of once-common species to dwindle or disappear altogether over the past 40 years - by up to 80 per cent in some cases.

But while the Island continues to fare better than most places, several species, like the northern bobwhite and eastern meadowlark and some sparrow species which have declined precipitously across the Northeast, also have disappeared or are in deep trouble here.

"It's pretty well known that populations of most bird species, in at least the eastern U.S. have been declining," said Matt Pelikan, a lifelong birder and Islands program director for The Nature Conservancy.

"But my sense is we are doing better than most of the rest of the region. A lot of species are hanging in with pretty solid, stable numbers," he added.

Nonetheless, he enumerated several species in decline:

"The vesper sparrow, which used to be a common breeder here a few decades back, hardly even occurs here as a migrant anymore. The eastern meadowlark is another one which no longer breeds here. We get them as wintering birds."

The Audubon report cited a national decline of 72 per cent in eastern meadowlarks.

"The bobolink is another species which has disappeared as a breeder in the last five or six years. There used to be a breeding population out at Katama, but that seems to have blinked out," said Mr. Pelikan. He continued:

"The grasshopper sparrow is a species the conservancy and other organizations have been trying very hard to salvage as a breeding bird here. I've done a couple of surveys this spring and haven't turned any up."

But in contrast to much of the rest of the country, on the Vineyard the decline in some species is due to increased tree cover.

Susan Whiting, another veteran birder and co-author of a book on the birds of the Vineyard, said the Island picture reflects the national one.

"It's pretty much along the same lines, "she said. "There's just a general decrease in numbers, and there's no simple answer.

"In general I would say there have been decreases in some of the warbler species and increases, unfortunately in brown-headed cowbirds, which are parasitic," she added.

Her coauthor, Barbara Pesch, attributed the decline in some other species to the increase in skunk and raccoon populations on the Island.

"The ground nesters have gone away because of our skunks and raccoons that eat the eggs," Mrs. Pesch said. "Things like pheasants, quail and bobwhites have declined because of egg destruction."

Indeed the bobwhite population has fallen 82 per cent across the U.S. and 99 per cent in Massachusetts, according to the Audubon study, which was compiled from national Christmas bird counts.

Although the Vineyard also participates in the Christmas count, Mr. Pelikan said it was of only limited use in determining what was happening to bird numbers on the Island.

"The Christmas bird count gives indications of resident species, but doesn't have anything much to say about migratory birds, because they are mostly gone by the time the count takes place," he said.

And changes happening elsewhere in the country have the greatest impact on those migratory species, he said.

"They go back to the wintering area and find it's been converted to a farm or coffee plantation or something," he said. "So there is no real quantitative evidence of what's going on on the Vineyard. But anecdotally, my sense is we are doing better than most of the rest of the region. A lot of species are hanging in with pretty solid, stable numbers."

He said a couple of species have increased in numbers as breeding birds over recent years, including the indigo bunting and rose-breasted grosbeak.

"With the indigo buntings, about four years ago there was a big early spring fallout of premature arrivals, and some of them stuck around and bred successfully, which made the nucleus of a little Island population," Mr. Pelikan said.

Both Mr. Pelikan and Ms. Whiting said there is evidence that climate change is bringing new species to the Island. Southern species which are spreading north as the climate warms include cardinals, mockingbirds, Carolina wrens, black and turkey vultures and Mississippi kites, she said.

"These are things which as kids we never saw on the Vineyard. But we've lost meadowlarks and we've lost grasshopper sparrows, so it's pretty depressing in that regard."

But Mr. Pelikan said whatever the picture for migratory birds, for those that nest on the Island things are looking pretty good.

"I've been doing a breeding bird survey for five or six years now - it's a U.S. Geological Survey national project - and it seems like over that period, numbers of most things have been pretty constant," he said.

Catbirds, common yellowthroat and eastern towhee all remain common on the Vineyard.

"There's good news too for some of the rare species like northern pareula, which is listed under the state endangered species act, but which still has a viable breeding population here," Mr. Pelikan said, adding:

"Every indication I have is that the majority of our bird populations are doing reasonably well and better than most on the mainland."

A more comprehensive picture of the Island bird population is expected to be available by year's end, when Ms. and Mrs. Pesch's updated edition of the Birds of Martha's Vineyard is due to be finished.

The book will use data from the Christmas bird count to compare numbers and species makeup of the Island bird life now, compared with 23 years ago, when they published the first version of their book.